An intrinsic biochemical concentration sensor using a polymer optical fibre Bragg grating

W. Zhang; D. J. Webb; G.-D. Peng

doi:10.1117/12.922279

25 April 2012 An intrinsic biochemical concentration sensor using a polymer optical fibre Bragg grating

W. Zhang, D. J. Webb, G.-D. Peng

Proceedings Volume 8426, Microstructured and Specialty Optical Fibres; 842618 (2012) https://doi.org/10.1117/12.922279
Event: SPIE Photonics Europe, 2012, Brussels, Belgium

Abstract

A new type of fibre-optic biochemical concentration sensor based on a polymer optical fibre Bragg grating (POFBG) is proposed. The wavelength of the POFBG varies as a function of analyte concentration. The feasibility of this sensing concept is demonstrated by a saline concentration sensor. When polymer fibre is placed in a water based solution the process of osmosis takes place in this water-fibre system. An osmotic pressure which is proportional to the solution concentration, will apply to the fibre in addition to the hydraulic pressure. It tends to drive the water content out of the fibre and into the surrounding solution. When the surrounding solution concentration increases the osmotic pressure increases to drive the water content out of the fibre, consequently increasing the differential hydraulic pressure and reducing the POFBG wavelength. This process will stop once there is a balance between the osmotic pressure and the differential hydraulic pressure. Similarly when the solution concentration decreases the osmotic pressure decreases, leading to a dominant differential hydraulic pressure which drives the water into the fibre till a new pressure balance is established. Therefore the water content in the polymer fibre - and consequently the POFBG wavelength - depends directly on the solution concentration. A POFBG wavelength change of 0.9 nm was measured for saline concentration varying from 0 to 22%. For a wavelength interrogation system with a resolution of 1 pm, a measurement of solution concentration of 0.03% can be expected.

Citation Download Citation

W. Zhang, D. J. Webb, and G.-D. Peng "An intrinsic biochemical concentration sensor using a polymer optical fibre Bragg grating", Proc. SPIE 8426, Microstructured and Specialty Optical Fibres, 842618 (25 April 2012); https://doi.org/10.1117/12.922279

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